Liposomes, which are closed vesicles consisting of bilayers of phospholipids as major constituents of biological membranes, have been used for researches as a biological membrane model, and uses thereof for drugs and cosmetics as a microcapsule for enclosing and delivering a drug have been attempted for many years. In the field of cosmetics, in particular, liposomes attract attentions, because they are valuable forms as microcapsule, and phospholipids themselves as constituents of liposomes are highly safe amphiphilic substances derived from biological membranes.
Uses and functions of liposomes have been diversified, and developments of uses for cosmetics and skin external preparations have also been attempted. From the viewpoint of beautifully showing skin, there are desired those not only having whitening effect and moisturizing effect, but also imparting firmness and tightness as well as elasticity of the skin to such an extent that the effects can be actually realized. As a result, there have been proposed techniques for preparing liposomes aiming at realizing high moisturizing effect of cosmetics and so forth by adding liposomes constituted with phospholipids to them. For example, there have been proposed liposomes containing hydrogenated soybean phospholipids having a phosphatidylcholine content not lower than 90 mass %, cholesterol, N-acylamino acid salt, and a copolymer comprising 2-methacryloyloxyethylphosphorylcholine and butyl methacrylate (for example, refer to Patent document 1).
Many techniques concerning liposomes have been examined, including not only those concerning liposomes themselves, but also those concerning cosmetics and external preparations containing liposomes. Such techniques may realize application of the usefulness of liposomes to cosmetics or skin external preparations to further increase added values of the preparations.